Hey Shadowmeph,
i think you forgot to set the permissions during the installation?
there are 2 options.
Option1:you can try the following: open a terminal enter
the following lines depents on your linux distrubution...
sudo chmod 777 /opt/PlaneShiftor
su chmod 777 /opt/PlaneShiftor
sudo su chmod 777 /opt/PlaneShiftor
login as root and then chmod 777 /opt/PlaneShift
Option2:is to reinstall PlaneShift and install it again .. and don't forget set the permission during the install on 777 and the group "your linux login name"
i hope it will help.